I have an XEM 2.1.1 installation with two XE instances. Whenever I log into either wiki instances and create or edit a page, I receive 403 forbidden for any URL with "/xwiki/bin". Below are some of the URLs requested but fobidden.
This only occurs when the user account is created/registered in one of the wiki instances. The user account used to administer the XEM instance is able to access the content.
XEM is setup to use Path-based resolution.